Testing of fuel filters using thermography

ABSTRACT

A coalescer element that functions as a filter for aircraft fuels is connected by means of a bearing surface to a heated air supply. The coalescer element is slowly rotated and scanned by means of an infrared device for sensing temperature on the outer surface of the fuel filter. The infrared scanner supplies signals to a color or black and white video screen which displays thermograms of the surface of the fuel filters. Non-uniform high temperatures on the surface of the filter, indicative that the filter is faulty, on being scanned by the scanner are displayed as a light color or light shade on the thermogram indicating a flaw in the coalescer element.

United States Patent [191 Pontello TESTING OF FUEL FILTERS USINGTIIERMOGRAPI-IY [75] Inventor: Anthony P. Pontello, Springfield, Pa.

[73] Assignee: The United States of America as represented by theSecretary of the Navy, Washington, DC.

22 Filed: Sept. 25, 1972 [21] Appl. No.: 292,013

14 1 Feb. 12, 1974 Primary Examiner-Herbert Goldstein Attorney, Agent,or Firm-R. S. Sciascia; Henry Hansen; Arthur A. McGill [57 ABSTRACT Acoalescer element that functions as a filter for aircraft fuels isconnected by means of a bearing surface to a heated air supply. Thecoalescer element is slowly rotated and scanned by means of an infrareddevice for sensing temperature on the outer surface of the fuel filter.The infrared scanner supplies signals to a color or black and whitevideo screen which displays thermograms of the surface of the fuelfilters. Nonuniform high temperatures on the surface of the filter,indicative that the filter is faulty, on being scanned by the scannerare displayed as a light color or light shade on the thermogramindicating a flaw in the coalescer element.

9 Claims, 2 Drawing Figures l l I l I l I 1 TESTING OF FUEL FILTERSUSING THERMOGRAPI-IY STATEMENT OF GOVERNMENT INTEREST BACKGROUND OF THEINVENTION The present invention generally relates to the testing offilters for'defects and more particularly to a nondestructive testing ofall coalescer elements used for jet fuel filtering.

Coalescers are used prior to refueling aircraft, in fuel systems at airstations and aboard refueling trucks to remove harmful contaminants fromjet fuels. These filters can also serve to reclaim previouslycontaminated fuel and prevent the fuel from being disposed of as wastematerial. Therefore, a critical need exists to develop a method fortesting all coalescer elements to be used without destroying theireffectiveness.

Limited performance of coalescer elements due to faulty material and/orconstruction can result in serious damage to fuel systems that can beboth dangerous and costly. To eliminate this damage, a need exists for ahigh level of quality control by the manufacturers of the elements. Mostpresent day methods of testing employed in the quality control of theelements are de- "structive. These tests comprise subjecting coalescerelements to liquids having solid and water contaminants. Due to thedestructive nature of the test, only a limited number in a batch can betested. Experience has shown that an appreciable number of elements froma batch which passed this test is often defective.

A non-destructive test of a coalescer element has previously beendescribed by applicant in U. S. Pat. office application Ser. No.175,238, now US. Pat. No. 3,736,790, patented June 5, 1973 in which afluorescent light source is utilized in conjunction with a liquidcrystal coating placed on the surface of the element to determine flaws.

While the above system works well in providing nondestructive testing,it requires coating the filter which tends to become more costly andtime consuming than the present invention.

SUMMARY OF THE INVENTION Accordingly, it is a generalpurpose and objectof the present invention to provide an improved test for coalescerelements. It is a further object to provide an improved non-destructivetest. Additional objects are to have the test more rapid and inexpensiveand less complex than those tests heretofore known.

This is accomplished according to the present invention by providing adifferential air pressure across the coalescer element with the higherpressure on the inside of the element and lower pressure on the outersurface. The outer surface is scanned by infrared detectors. Signalstransmitted from the detectors form a thermogram of the element on acolor or black and white video screen with differences in color orshading on the thermogram depicting differences in temperatures on thesouter surface of the element. The differences in temperature are theresult of flaws in the coalescer element creating a change intemperature of the air passing through.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a diagrammatic arrangement ofa test structure, partially in cross section of the present invention;and

FIG. 2 is a view of the housing shown in FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENT Thermography involves the use ofequipment for detecting temperature differences on an object in the formof a thermal picture called a thermogram. The

, thermogram is formed utilizing natural infrared radiation signalswhich vary with the surface temperature of the object. The colors orshading displayed in a thermogram show various temperature changes withthe lighter colors or shades, if the picture is displayed in black andwhite, representing the higher temperatures. Thermograms formed by highfrequency infrared scanning produce a real-time picture on a monitorscreen in either color or black and white.

Referring now to the drawing and more particularly to FIG. 1, there isshown a pressurized air supply 10, that may be cylinders of pressurizedair, a supply available in a building, or any other suitable means. Theair supply is connected to an air motor 1 1 through air pressureregulator 12, shut off valve 13, and pressure gage 14 by means ofsuitable piping 15. The regulator 12 is adjusted to supply apredetermined air pressure for air motor 11 whose speed is a function ofthe air pressure supplied.

Air motor 11 is connected to tachometer generator 20 through connectingrod 21. The tachometer generator 20 provides a signal for read-out ofthe speed air motor 11 on rpm gage 22. The primary function of motor 11is to rotate coalescer element 30. This is accomplished by mechanicallyconnecting the motor 11 output to gear box 31 through rod 32. The gearbox 31 provides angular displacement of the driving force and, inaddition, may provide a reduction ratio of rpm as required. A linkage 33connected to gear box 31 provides a driveto rod 34 that passes throughand engages the inner rotating element 35 of bearing 36. Lock nuts 46and 37 secure rod 34 to element 35. The outer stationary element 38 ofbearing 36 is secured to an upper plate of housing 39 by means of bolts40 and 41 having respective nuts 42 and 43. Rod 34 is threaded to aT-shaped coalescer cap with a nut 51 compressing the top of cap 50. Anupper annular end cap 52 and coalescer element 30 provide a press fitfor cap 50.

A lower annular end cap 53 of coalescer element 30 has a hollowcylindrical bearing insert 54 press fitted to both the annular openingin the end cap 53 and the coalescer element 30. The bearing insert 54 isalso press fitted to the inner rotating element 55 of bearing 56. Theinner element 55 is raised slightly above outer stationary element 57 onbearing 56 so that element 55 may rotate in unison with coalescerelement 30, end cap 53 and insert 54.

Outer stationary element 57 of bearing 56 has an inner annular surfaceconnecting to an annular ridge of lower bearing base support 58. Thisconnection may be a press fit or element 57 can be welded or affixed inany other manner to base support 58 so that the two are stationary withrespect to' eachother. Support 58 is then welded or otherwise affixed tolower plate 59. Strips connect upper and lower plates 45 and 59 ofhousing 39. Clamps 66 having screws 67 locate housing 39 on base member70. Base member 70 is a support for housing 39 and other components andmay be affixed to a wall or have legs for support.

The air supply 10 is also connected to heating element housing 75through pressure regulator 76, shut off valve 77 and pressure gage 78 bymeans of piping 79. Heating element 80 may have either manual orautomatic rheostat control for supplying a predetermined temperature.The housing 75 is connected to base member 70 by means of welding orother known methods.

An infrared scanner 85 provides a 180 scan of the outer circular crosssectional area of coalescer element 30. An electrical signal is providedfrom infrared scanner 85 to thermogram dispaly unit 86.

FIG. 2 shows a view of housing 39 having an upper plate 45 and lowerplate 59 with respective openings 95 and 96. Strips 65 connect upper andlower plates 45 and 59 to each other. The strips 65 can be connected toupper plate 45 by means of screws for ease in assembling anddisassembling the entire arrangement.

The operation of the device will now be explained with reference to thefigure. The air supply 10 is pressure regulated by regulator 12 andsupplied to air motor 11 so as to rotate the motor at such a speed as tosupply a rotational speed of 10 15 rpm to coalescer 30 through theassociated linkage connecting motor 1 1 to coalescer 30.

The air supply 10 is also connected to coalescer element 30 throughpiping 79, regulator 76 set to approximately 25 psi presure, valve 77,heating element 80 set to a temperature of 1 13 135 F, and elements 70,59, 58 and 54. This supply of air permeates the coalescer element 30from the inside through the outside surface. The infrared scanner 85then provides a signal to thermogram display unit 86 that displays athermogram 87 showing a flaw as the light portion in the center ofthermogram 87.

Portions of the coalescer element in which there are no fiaws provide atemperature drop of approximately 3 F while those with serious flawssuch as holes may produce only a 56 F temperature drop at the place theflaw exists. This would mean that a temperature on the inside of acoalescer element of 125 F would be approximately 122 F at the outsideof the element at portions without a flaw and at higher temperatureswhere a flaw is present. The thermography equipment is sensitive enoughto provide a thermogram wherein temperature differences of l/l F can bedistinguished.

There has therefore been described apparatus and means fornon-destructive testing of filter elements. This is accomplished aspreviously described by taking into account the differences intemperature differentials across the filter element depending on whethera flaw exists in the element or not.

It will be understood that various changes in the details, materials,steps and arrangements of parts, which have been herein described andillustrated, in order to explain the nature of the invention, may bemade by those skilled in the art within the principle and scope of theinvention as expressed in the appended claims.

What is claimed is: l. A filter testing arrangement comprising: apressurized air supply for supplying pressurized air;

a heating element connected for heating said pressurized air;

a filter element connected for receiving said air supply on the insidesurface of said filter element so as to provide a temperature dropacross said filter element from the inside surface to the outsidesurface of said filter element on said pressurized air passing through;

sensing means for scanning the outside surface of said filter elementand providing output signals indicative of temperatures on said outsidesurface of said filter element; and

display means connected to receive said sensing means output signals fordisplaying information indicative of said temperatures on said outsidesurface.

2. A filter testing arrangement according to claim 1 further comprising:

rotation means for rotating said filter element.

3. A filter testing arrangement according to claim 2 wherein saiddisplay means further comprises a video screen for displayingthermograms.

4. A filter testing arrangement according to claim 3 wherein saidsensing means comprises an infrared scanner.

5. A filter testing arrangement according to claim 4 wherein said filterelement comprises a coalescer element used in filtering aircraft fuel.

6. A filter testing arrangement according to claim 5 wheerein saidrotation means further comprises:

an air motor connected to receive said pressurized air;

an air pressure regulator connected to regulate the pressure of saidpressurized air to said air motor;

a tachometer-generator connected to said air motor;

an indicating gage connected to said tachometergenerator for indicatingthe rotational speed of said air motor;

a first slidable bearing connected intermediate said air motor and saidcoalescer element; and

a second slidable bearing connected intermediate said heating elementand said coalescer element.

7. A method of non-destructive testing of a coalescer element used infiltering aircraft fuel, comprising the steps of:

passing heated pressurized air from the inside surface to the outsidesurface of the coalescer element; scanning the outside surface of saidcoalescer element with an infrared scanner; and

displaying the outside surfce of said coalescer element in the form of athermogram.

8. A method of non-destructive testing of a coalescer 55 elementaccording to claim 7 further comprising:

rotating said coalescer element with reference to said infrared scanner.

9. A filter testing arrangement comprising:

a pressurized gas supply for supplying pressurized a heating elementconnected for heating said pressurized gas;

a filter element connected for receiving said gas supply on the insidesurface of said filter element so as to provide a temperature dropacross said filter element from the inside surface to the outsidesurface of said filter element on said pressurized gas passing through;

6 means output signals for displaying information indicative of saidtemperatures on said outside surface.

1. A filter testing arrangement comprising: a pressurized air supply for supplying pressurized air; a heating element connected for heating said pressurized air; a filter element connected for receiving said air supply on the inside surface of said filter element so as to provide a temperature drop across said filter element from the inside surface to the outside surface of said filter element on said pressurized air passing through; sensing means for scanning the outside surface of said filter element and providing output signals indicative of temperatures on said outside surface of said filter element; and display means connected to receive said sensing means output signals for displaying information indicative of said temperatures on said outside surface.
 2. A filter testing arrangement according to claim 1 further comprising: rotation means for rotating said filter element.
 3. A filter testing arrangement according To claim 2 wherein said display means further comprises a video screen for displaying thermograms.
 4. A filter testing arrangement according to claim 3 wherein said sensing means comprises an infrared scanner.
 5. A filter testing arrangement according to claim 4 wherein said filter element comprises a coalescer element used in filtering aircraft fuel.
 6. A filter testing arrangement according to claim 5 wheerein said rotation means further comprises: an air motor connected to receive said pressurized air; an air pressure regulator connected to regulate the pressure of said pressurized air to said air motor; a tachometer-generator connected to said air motor; an indicating gage connected to said tachometer-generator for indicating the rotational speed of said air motor; a first slidable bearing connected intermediate said air motor and said coalescer element; and a second slidable bearing connected intermediate said heating element and said coalescer element.
 7. A method of non-destructive testing of a coalescer element used in filtering aircraft fuel, comprising the steps of: passing heated pressurized air from the inside surface to the outside surface of the coalescer element; scanning the outside surface of said coalescer element with an infrared scanner; and displaying the outside surfce of said coalescer element in the form of a thermogram.
 8. A method of non-destructive testing of a coalescer element according to claim 7 further comprising: rotating said coalescer element with reference to said infrared scanner.
 9. A filter testing arrangement comprising: a pressurized gas supply for supplying pressurized gas; a heating element connected for heating said pressurized gas; a filter element connected for receiving said gas supply on the inside surface of said filter element so as to provide a temperature drop across said filter element from the inside surface to the outside surface of said filter element on said pressurized gas passing through; sensing means for scanning the outside surface of said filter element and providng output signals indicative of temperatures on said outside surface of said filter element; and display means connected to receive said sensing means output signals for displaying information indicative of said temperatures on said outside surface. 